Davit.



H. F. NORTON.

DAVT.

APPLICATION FILED APR. 24. i917.

Patented Nov. 13, 1917'.

kamm.

WHW/woo attorney.

UNITED sfra'rns rarnnr onirica DAvI'r.

Specification of Letters Patent.

Patented Nov. 13, 1917.

Application ledAprl 24, 1917, Serial No. 164,148.

To all whom t may concern:

Be it known that I, HAROLD F. NORTON, a citizen of the United States, residing at Newport News, in the county of Viarwick and State of Virginia, have invented certain new and useful Improvements in Davits, of which the following is a specification.

The present invention relates to devices for hoisting and lowering boats over the side of a ship.

It is the object of my invention to so construct the davit and the fall that the effort required to move the loaded davit in or out is substantially uniform at all points of the travel.

It is a further object of my invention to so arrange the parts that, when the head of the davit is inboard of the foot, the tendency of the load, if any, will be to push the davit outboard of the foot and, when the head of the davit is outboard of the foot, the tendency, if any, of the load will be to push the davit inboard, thus tending to counterbalancel the weight of the davit arm and fittings thereon.

To carry out theseobjects I have made such disposition of the parts that the direction of the resultant force of the load on the one side and the lifting force on the other side is substantially coincident with the davit arm at all times, such disposition making the stress on the davit arm virtually independent of the length of the davit arm and consequently ofthe athwartship overhang.

For a fuller understanding of my invention, I refer to the appended drawings, in which- Figure 1 is a view looking at the davit at right angle to the plane of its travel; and

Fig. 2 is a view looking at the davit in the direction of its travel.

In the drawings, 1 represents the deck of the ship. The davit arm 2 is pivoted at its lower end on a support 30 to swing in an athwartship plane. Lugs 3 and 4l on the davit, bolt 5, nuts 6 and 7 and flanges 8 and 9 represent conventional elements of construction for pivoting the kdavit arm 2 to support 30.A The frame 10 supports the mechanism for operating the davit. This mechanism constitutes no part of the present invention, and may preferably be of the kind described in my prior Patent No. 1,071,7 83. The screw gear 11 is merely representative of any and all means that are applicable for the particular purpose. The screw gear 11 may be advantageously connected to the davit arm 2 by a universal ]oint composed of the pivotal elements 12 and 13 at right angles to each other. At the other end, the screw gear is pi'votally supported on the frame 10, preferably by means of a universal joint, such as described in my prior patent. rIhe numeral 14 represents apivot connection on a bearing 15 attached to the frame 10. The screw gear 11 is operated by a hand-wheel 16er other suitable device and is so dimensioned that by its operation the davit arm 2 can be n'shifted from one extreme intended working positionto the other.

At the upper end of the davit arm 2 is mounted a pulley or sheave 17.

An auxiliary pulley or sheave 18, which constitutes the principal feature of my present invention, is mounted Yon an arm 19 which itself is conveniently supported on the frame 10 and suitably braced as by means of a brace rod 20. This pulley is disposed approximately in the general plane of travel of the davit arm 2, being sufficiently out of that plane so as not to interfere with thedavit arm in its motion. The position of the pulley is intermediate the extreme working positions of the davit arm and substantially vertically above the pivot point of the davit arm. The importance of this disposition of the pulley 18 lies in the fact that the resultant force of the load on the one side and the lifting power on the other side acts substantially in the direction of the length lof the davit, t'. e., along the davit. It is thus obvious that there can be substantially no athwartship bending moment on the davit arm, thus making the intensity of the stress in the davit arm virtually independent of the length of the arm and of the athwartship overhang. Itis further obvious that the force required to move the davit arm from one side to the other is substantially uniform throughouty its travel.

lVhile the advantage thus gained is the principal object of the invention, I prefer to so determine the relationship of the auxiliary pulley 18 and the davit arm 2 that theA resultant force acting on the arm has a slight but distinct tendency to push the davit arm, when it is in one extreme working position, as shown in Fig. 1, to the opposite side. The extreme working position referred to is that when the boat is ready to be launched. It is at this moment obviously desirable to give an impetus to the starting motion to bring the boat underway. The location of the pulley may simultaneously be so chosen, there being sufcient latitude for the arrangement, that in the extreme opposite working position, when the boat is suspended outboard ready to be hauled in, the resultant force has a tendency to move the davit arm and the boat inboard. The reason for the desirability of this feature is equally obvious.

In Fig. 1 the various positions of the davit arm are indicated by the letters a, c, CZ and e, respectively. R indicates the rope pass ing from the winch drum D, which is suitably mounted in frame 10, to the pulley 18, to the pulley 17, to the boat. The arrow indicates the direction of the resultant force. In position a, the direction of the resultant force forms a slight but distinct angle with the axis of the davit arm toward the outboard side. In position Z) this angle is smaller and in position c it is substantially Zero. In position d it forms again a slight angle but toward the inboard side. In position e it is substantially zero, but just as soon as the davit arm is beingy moved inboard, the tendency of the resultant force is to augment that motion.

By this arrangement not only the weight of the davit arm is compensated for, but a distinct impetus may be given to the arm to facilitate its motion to a certain extent not incompatible with the general object of the invention to make the force necessary for moving the davit arm substantially uniform.

While I have shown the single guide sheave 18, I may find it desirable under certain conditions to use two or more guide sheaves. The illustration of one is characteristic of the use of a plurality.

It is understood that my device is susceptible of certain changes within the scope of the invention and what is shown is intended merely as an illustration of the broad principle underlying my invention.

It is also obvious that my invention is not only applicable to a davit structure, but is capable of broader uses, as in connection with derriclrs and other loadstransferring devices of similar character.

l. In an apparatus for transferring a load, the combination of a beam pivotally supported at its lower end, a pulley at its upper end, an auxiliary pulley supported adjacent the beam independently thereof and a rope passing over the two pulleys, the second pulley being so positioned that the direction of the resultant force acting on the beam lies substantially along the beam for all posiionls of the beam during the transfer of the 2. In an apparatus for transferring a load, a beam pivoted at its lower end and adapted to travel in a substantially vertical plane, a pulley at its upper end, an auxiliary pulley substantially in the said vertical.

Vplane and independent of the beam, and a rope passing over the said pulleys, the position of the auxiliary pulley being such that the direction of the resultant force acting on the beam lies substantially along the beam for all positions of the beam during the transfer of the load.

3. In an apparatus for transferring a load, a beam pivoted at its lower end and adapted to travel in a substantially vertical plane, a pulley at its upper end, an auxiliary pulley substantially in the said vertical plane and independent of the beam, and a rope passing over the said pulleys, the position of the auxiliary pulley being such that the beam approximately bisects the angle formed by the rope between the auxiliar pulley and the load for all positions of the beam during the transfer of the load.

Ll. In an apparatus for 'transferring a load, a beam pivoted at its lower end and adapted to travel in a substantially vertical plane, a pulley at its upper end, an auxiliary pulley mounted independently of the beam, a rope passing over the said pulleys, the position of the auxiliary pulley being such that the resultant force acting on the beam acts substantially along the beam during the major part of its travel, but has at the beginning of the transfer a distinct tendency to move the beam to the opposite side.

5. In an apparatus for transferring a load, a beam pivoted at its lower end and adapted to travel in a substantially verti cal plane, a pulley at its upper end, an auxiliary pulley mounted independently of the beam, a rope passing over the said pulleys, the position of the auxiliary pulley being such that the direction of the resultant force acting on the beam lies substantially along the beam during the major part of its travel, but that the resultant force has a distinct tendency in the extreme positions of thcp beam to move the beam to the opposite s1 e.

6. The combination of a davit free to turn in a substantially vertical plane, a pulley carried at its upper end, an auxiliary pulley substantially in the said vertical plane and so positioned intermediate the extreme working positions of the davit that the resultant force acting on the davit acts substantially along the davit` in every position thereof.

7. The combination of a davit free to turn in a substantially vertical plane, a pulley carried at its upper end, an auxiliary pulley substantially in said vertical plane and intermediate the extreme working positions of the davit, a rope passing over the said pulleys, the position of the auxiliary pulley being such that at the beginning of the transfer of the load the resultant force aeting on the davit tends to move it to the opposite position and that during the remainder of the transfer the resultant force acts substantially along the davit.

8. The combination of a davit free to turn in a substantially vertical plane, a pulley carried at its upper end, an auxiliary pulley substantially in said vertical plane and intermediate the eXtreme Working positions of the davit, a drum and a rope passing from the drum over the auxiliary pulley and the davit pulley to the load.

9. The combination of a davit arm free to turn in a substantially vertical plane, a pulley at its upper end, and an auxiliary pulley in a fixed position substantially vertioally above the pivot of the davit arm.

10. The combination of a davit arm free to turn in a substantially vertical plane, a pulley at its upper end, a :trame on the inboard side of the davit. a Winch drum on the said frame, a guide pulley mounted on the said frame, a rope passing from the drum over the guide pulley and the davit pulley, the position of the guide pulley being such that the resultant force acting on the davit arm is substantially coincident with the arm.

11. The combination of a davit arm free to turn in a substantially vertical plane, a

pulley at its upper end, a frame on the inboar'd side of the davit, a guide pulley mounted on the said frame and positioned substantially vertically above the pivot of the davit arm, a Winch drum on the said frame, and a rope passing from the drumv sects the angle formed by the rope from' thev guide over the top of the beam to the load.

13. A davit construction comprising a davit arm free to turn in a denite plane, a rope passing over the upper end of the davit arm to a boat, means intermediate the free end of the rope and the top of the davit arm and substantially in the plane of travel of the davit arm for guiding the rope, the position of the guiding means being such that the davit arm in eac-h position during its travel substantially biseets lthe angle formed by the rope from the guide over the top of the davit arm to the boat.

In testimony whereof I aix my signature. l

HAROLD F. NORTON.

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of Patents, Washington, D. C. 

